Users of Compressed Air-Line Breathing Apparatus - Beware

The proposal you mention for lesser quality breathing air is an idiot's approach to a constant problem. Air specs should be tighter, not looser. No matter what the standards say, the best supplied compressed breathing air respirator systems include a CO monitor on the discharge end of the pump. This precludes the one time irregular operation of the pump or the constant use of it.

In the USA, testing of the air produced in a breathing air pump is required at least twice a year. This is done by an independent lab and must be obtained before any customer uses it. OSHA and PEOSHA's only set the minimum standards for breathing air. These can be surpassed and maintained at higher levels of purity.

Is your system the type that: uses a 1/2 face respirator; full face respirator mask; excess air flow hood; 5 minute escape bottle; or some other arrangement?

Good Luck, Old Salt

There are various standards around the world, and although there is nothing to stop anybody improving on the minimum required, most users do not have the expertise to assess what is best. They resort to applying the appropriate standard on the assumption that it will be adequate. The alarm level of the CO monitor needs to be set to something.

My work involved compressed breathing air purification. Compact multi-stage devices to remove toxic contaminants. Being portable, wall-mounted or floor standing, and connected in the air-line to interface between whatever respirator was being used and the compressor.

All this at medium pressure - up to 10 bar. We were not involved in high pressure purifiers at all. or supplying respirators.

Good information and a reasonable suggestion as well.

.

One minor point:

'...There is no CO in the natural atmosphere,...' isn't correct. Most of the CO in the atmosphere is natural in source.

Re: Users of compressed air-line breathing apparatus - beware

Please let me clarify the statement.

ISO2533 gives the gases in the natural atmosphere and CO is not listed. It is only present in trace quantities and in this context the amount has little effect, if any, during risk assessments.

I thank you for the link. What happens here I think is the amount produced, seemingly in big numbers, either naturally or man made, accounts only for the near zero average trace quantities on a global scale.

In practice of course, it is a localised problem, where anyone near the source of CO production (coal-mines, traffic, industry, over-heating compressors, etc) will be hit by unknown high levels of CO before it naturally disperses to 'safe' levels - which itself could take a long time.

10ppm is well below OSHA limits.

Here's their guide:

http://www.brandtinst.com/biosystems/appnotes/Downloads/23.%20Setting_Confined_Space_Gas_Detector_Alarms.pdf

Hello Bricktop re 5.

The CO needs to be well below OSHA limit.

Please note that the link refers to the Occupational Exposure Limit (OEL) of the workplace ambient atmosphere, whereas the standard refers to the quality of the life support air fed to the respirator - which must be much cleaner to allow for inward leakage.

Respirators are selected on the basis of permitted inward leakage, such that the total contamination in the mask does not exceed the OEL. A mask already filled with contaminated compressed air will not be fit for purpose.

And in the link, if the air in the confined space exceeds the OEL, then a respirator will be required.

CO in the atmosphere does occur but is distributed at fraction of a mg/L and I think about 0.1 mg/L. It may be higher around volcanic or bush fire incidents but on the whole it is low. So to say there is none in the atmosphere is correct or not correct if you are comparing it to 10 mg/L. Or a little of both but it is the relativity of the concentration.

The concern is with self breathing apparatus used by many including scuba divers as well as emergency work. I had once wanted to use compressed air in ground water wells to enhance environmental work. I could buy very clean compressors but by the time one added the filtering expense was high. And we were not even considering CO in water as a problem. It was all the other nasty stuff that compressors put out. The short is that we resorted to chemically available oxygen as found in H2O2 and it not a problem for some approved grades.

If the concern is with CO in breathing and atmospheric distribution is but a fraction of a mg/L then to allow something more reason for review. If 5 mg/L is the deemed standard accepted internationally, use that standard. I would prefer my Scuba tank filled at least to some tight standard. Who checks the standard when you go to a resort in the south? Or here. Here are the EPA standards. Why so different?

I have resorted to simple snorkelling as I am too lazy to drag equipment around. And the air is cleaner.

Re Kevinm post 7

Just a point of accuracy of units for comparison. Being lazy I have used ppm but strictly it is ppm on a volume basis and should be ppm(v).

The standard is based on ml/m³ (it's an ISO thing to use ISO approved units) whereas everybody uses ppm in practice. which means ppm(v) .

You refer to units of mg/L - which has to be converted to ppm for comparison.

Diving is an extremely important aspect of compressed air quality but this stand excludes devices used exclusively under water, for aviation, for medical use or resuscitation.

However you make a valid point about quality control that is fundamental to your safety but difficult to monitor due to lack of clear guidance and policing, but it is getting better..

Standards for respiratory protection air, and for diving air, have just been established by CEN for Europe and will be published soon as EN12021. The CO will be 5ppm.

I would add that it is not whether it is 5ppm or 10ppm of CO when viewed out of context is safe that matters, but the underlying attitude to health and safety that if there is no CO in the natural atmosphere then the presence of any CO in the breathing air must be a fault condition.

Thus allowing 10ppm so the fault can be ignored in a standard specifically designed to setthe quality of life-support air to provide respiratory protection is downright irresponsible.

I hope this helps.

Thanks. I worked in the water industry too long and forgot gas ratios. Confusing but you are right and it does make sense in gas ratios to use ppm(v).

The lack of confidence in the underwater industry is justified. And I agree wholeheartedly that to dumb down the standard when safety is paramount in any field of use is irresponsible. You are quite informative and thanks for posting the concerns.

Some clarification please, are we discussing SCBA's, Atmosphere-supplying respirator (ASR ), Powered air-purifying respirator (PAPR), Filtering facepiece (dust mask), Air-purifying respirator (APR), a compressed air supplied respirator/hood or some other supplied air system?

The initial OP seemed to indicate a compressed air supplied face mask with the required 5 minute escape bottle (mini SCBA), but some of the subsequent answers and clarifications of the OP seem to indicate otherwise.

Are the contaminants IDLH? What protection factors are you using? SCBA is 10,000' SAR is 1,000; a PAPR is 1,000; (these must all be Pressure-demand or other positive-pressure mode (e.g., open/closed circuit); a full-face cartridge filter is 100; and a half face cartridge filter is 50 for non-IDLH atmospheres. What are the exposure limits for the contaminants? For any of these that are not positive pressure the ratings are reduced considerably

Any air that is supplied by a compressor as it is used should have a CO and perhaps other materials sensors on them as the air is used. SCBA's should be filled from a certified air bottle filling compressor.

I would appreciate clarification on the type used.

Good Luck, Old Salt

To Old Salt re 8

This standard, ISO16975 pt 1, applies to all types of Respiratory Protective Devices (RPD) but excludes those used exclusively under water, in aircraft, medical life support and resuscitators. There is a part 2 as well - which is a condensed guide version.

All the types of respirators you mention are included under the RPD heading.

My interest however is only in the Supplied Breathable Gas devices using compressed air. either self-contained or airline connected by hose to a compressor. My interest is further limited to the quality requirements of the compressed air and in practice the medium pressure systems. I am not involved in ambient air compressors (low pressure pumps, blowers etc), or high pressure.

I have no direct involvement in the selection of the RPD. The ambient air could be well be IDLH and the supplied air device would need some form of additional escape device.

All these situations are covered by this e standard.

My OP was to draw attention to the CO aspect because I just think it is wrong for the standard to allow the use of compressed air with 10ppm of CO in it. It should be 5ppm at least. If anyone feels strongly as I do, then it would help if they could contact the standards making body in their own country to say so. ISO will respond to votes from each country.

horace40-

Please forgive my ignorance. My career was primarily in the USA chemical industry with a strong emphasis in safety and haz mat responses among others. These being based in the USA I had to understand, implement and maintain OSHA programs within their regulations and state osha regs. Either myself or my managers were responsible and if we didn't do things right it could result in deaths or at least substantial fines. Some of the stuff we used and made was some real nasty stuff.

That said I am not very familiar with other than OSHA regs. Never had to know anything else and never had the time to explore into any others. With that I am going to drop out of this discussion and leave it to those who have more knowledge, like yourself!

Good Luck, Old Salt

I have been working in the chemical industry for 40 years. (Has it really been that long? I must be an old fart!) I shudder to think of the unsafe things that we used to do. One that immediately comes to mind was the source of breathing air for guys entering confined spaces. The plant had two air compressors. One was for 90 psig "plant air" the other was 30 psig "instrument air". All of the instrumentation in those days was pneumatic (3-15 psi signal) and typically had a 30 psig supply. For a vessel entry, guys would simply hook up their masks to the nearest "instrument air" line. The scary part was that, whenever the instrument air compressor wasn't working right, they would simply open a valve and introduce nitrogen into the instrument air system. No special safeguards... just a ball valve!

It's a wonder and a blessing that nobody was killed.

I would think nearly any city street has ppm concentration above 5ppm and probably 10ppm on a busy street.....Here is a study done in Mexico some years ago....

"The aim of this study was to explore the CO exposure experienced by street ... In January 1991, CO measurements were taken at street level of selected avenues in the city ... ranged from 2.0 to 70.0 ppm with a mean concentration of 26 ppm."...

http://www.ncbi.nlm.nih.gov/pubmed/9857291